The present invention relates to a lamp socket adapted to be mounted in a circuit plate such as a printed circuit board or a flex circuit, and in particular, to an electric terminal for use in the socket.
Automobile dash panels typically have lamp assemblies mounted therein to provide visual indication and warning signals. The lamp assemblies are mounted in a circuit plate such as a printed circuit board or a flex circuit affixed to a panel. A common practice has been to provide a lamp assembly in the form of a socket and lamp, and attach the lamp assembly to the circuit plate by inserting the socket axially into an opening in the circuit plate, and then rotating the socket in order to lock the socket in the circuit plate. In so doing, electric terminals carried by the socket make electrical connection with the circuit, e.g., see Fitzgerald et al U.S. Pat. No. 5,160,277.
The terminals disclosed in that patent comprise an exposed upper contact portion and a shank portion which extends downwardly into the opening of the socket. The lower end of the shank portion is U-shaped, and a wire from the lamp is welded to the U-shaped portion. Although such a welded joint achieves a positive electrical connection with the lamp, the welding operation adds appreciable expense and effort to the manufacturing operation. Therefore, it would be desirable to enable the welding step to be eliminated without sacrificing the integrity of the electrical connection.
It is also important that good electrical connection be achieved between the terminals and the circuit of the circuit plate. The contact portion of each terminal described in the afore-mentioned patent comprises a generally arc-shaped plate presenting a convexly shaped contact surface which faces the circuit. When the socket assembly is installed in the circuit plate, the contact portion is depressed, and, in effect, rolls radially outwardly away from the socket axis so that the point of contact between the contact surface and the circuit is displaced along the contact surface. In effect, then, the contact surface slides radially along the circuit to wipe any oxide coating from the circuit to establish a positive electrical connection therewith.
Although the contact surface comprises a solid surface which is seemingly smooth, there will inherently exist minute irregularities (i.e., peaks and valleys) in the profile of the surface. It will be appreciated that the actual physical contact between the circuit and the contact surface will occur at only the three highest peaks which may, in effect, be considered to form together a point contact (as opposed to surface contact) between the circuit and terminal. If the oxide coating were not removed at that point, then the terminal could fail to make a proper electrical connection.
It would be desirable to provide greater assurance that a proper electrical contact will occur.
It would also be desirable to facilitate the insertion of the lamp/terminal assembly into the socket, and to effectively resist removal of that assembly from the socket.